Tertiary-butyl halide promoters in friedel-crafts catalyzed olefin polymerizations



Patented Jan. 1, 1952 TERTIARY-BUTYL HALIDE PROMOTERS IN 'FRIEDEL-CRAFTSCATALYZED oL-EFIN POLYMERQIZATIONS David C. Walsh, Jr., and Henry SchutzBay- ,town, Tern, assignors, by mesne assignments, to Standard GilDevelopment Company, Elizabeth, N. J., a corporation of Delaware NoDrawing. Application July 1, 1948, Serial No. 36,415

9 Claims. 1

The present invention is directed to an improved process for thepolymerization of low molecular Weight unsaturated hydrocarbons in thepresence of a Friedel-Crafts type catalyst. More particularly, theinvention is directed to the polymerization of mixtures of low molecularweight unsaturated hydrocarbons in the presence of a Friedel-Crafts type.catalyst and a promoter for the reaction.

This application is a continuation-in-part of our abandoned co-pendingapplication .Serial No.

737,726, filed March .27, 1.947.

Prior to the present invention it has been customary to polymerizetertiary olefins, such as isobutylene, alone .or in admixture withdiolefins, such as butadiene or isoprene, in the presence of aFriedel-Crafts type catalyst to obtain a product of higher molecularweight than the starting material such, for example, as polymers in thelubricating oil boiling range or rubberlike polymers. The process isextremely sensitive to impurities and it is necessary that expensiveexpedients be resorted to in order .to purify the reactants. Impuritieswhich are removed from the reactants comprise acidic material,unsaturated polymers of relatively low molecular weight, oxygenatedbodies and various other extraneous materials which may find their Wayinto the system in which the polymerization is effected. Thepurification steps comprise various chemical and physical treatingmethods to obtain the purified product.

It is desirable also to remove water from the unsaturated hydrocarbonssince water in appreciable quantities will hydrate the Friedel- Craftstype catalyst and render it less efiicient than when the reactants arein an anhydrous condition.

The nature of the impurities has made it difficult to obtain thereactant hydrocarbons in substantially pure condition. From time to timeit has, therefore, been necessary, in order to obtain best results, toincrease the concentration of the .Friedel-Crafts type catalyst which isemployed. Ordinarily, the catalyst is employed in a solution of anorganic halide in a concentra tion of about 0.1 to 0.5 gram of .aluminumchloride per 190 o. 0. of solvent. The usual solvent employed is analkyl halide, such as methyl chloride. In order to compensate for a dropin the eificiency of the catalyst, .at times it has been necessary toincrease the concentration of aluminum chloride to the upper limit givento keep the reaction rate at a constant level. The

adoption of this .expedient may result in the formation of apolymerization product having undesirable properties in view of theullpl'ed'lct able activity of these concentrations of catalyst solution.

In accordance with the present invention, the polymerization of lowboiling tertiary base olefins, alone or in admixture with low boilingconjugated diolefins, to form polymeric hydrocarbons in the molecularweight range of lubrieating oil and rubber-like polymers in the presenoeof a Friedel-Crafts type catalyst is improved by the addition to thereaction mixture of controlled amounts of tertiary butyl chloride ortertiary butyl bromide. It has been discovered that tertiary butylchloride or tertiary butyl bromide in the reaction mixture in an amounbetween .6 .and parts per million parts of hydrocarbon feed promotes thereaction and activates the catalyst to a degree that solutions of lowcatalyst concentration may be employed. Previous workers have reportedtertiary butyl halides to-have a poisoning efiect on the polymerizationcatalyst, thus adversely affecting the reaction. We have found thatwithin the concentration range mentioned above, the reverse is true andtertiary butyl chloride and tertiary'butyl bromide have a powerfulactivating .eifect.

Low boiling tertiary .base olefins which may suitably be employed in thepresent invention include isobutylene, 2-.methyl butene-B, z-nethylpentene-l, Z-methyl pentene-Z, 'B-methyl pen- :tene-2, 2,3dimethylbutene-l, 2,3-dimethyl butone-2, 3-methyl hexene-Z, 'S-methyl hexene-B,

3-.ethyl .butene-2, 2,3-diinethyl pentene-2, 2,4-dimethyl pentene-l,2,4-dimethyl pentene-2, 2,3,3-trimethyl vhutene-B, and higher tertiarybase olefins (or mixtures thereof, although weprefer to usesuch tertiarybase olefins that contain not more than -7 carbon atoms per molecule.

Low boiling eonl'ugateddiolefins which may suitably be employed in thepresent invention include, r-insgeneral, such conjugated diolefins as1,3-butadiene, 2-methyl --l,3.-. butadiene ,or isoprene, 2,3-dimethyl-l,3.-butadie.ne, 1,3-pentadiene, 2-methyl-1,3-pentadiene,2,3-dimethyl-1g3- .pentadie-ne, and the like or mixtures thereof,.havingpreferably not more than 7.carbon atoms per molecul SuitableFriedel-Crafts type catalysts which may .be employed in the presentinvention for the polymerization oftertiary bflSGOlEfiIlS ormixtures oftertiary base ,oleiins and conjugated dioleiins include A1013, AlBrg,A113, TiCh, Bfs, ZrCl4,-FeC13, ZnClz, SbCls, and the like. Although anyof the aforementioned Friedel- -Crafts type 3 catalysts may be employed,AlCls is preferred inasmuch as it particularly lends itself topolymerization reactions of the type with which this invention isconcerned. Irrespective of which particular Friedel-Crafts type catalystis employed, it is introduced into the reactants in the form of asolution, the catalyst being dissolved m a solvent for the catalyst,which does not react with the catalyst. Solvents having theaforementioned properties and which have been found to be suitableinclude methyl chloride, ethyl chloride, chloroform, ethylenedichloride, sulfuryl chloride, carbon bisulflde, and the like.

In the practice of the present invention, both the feed stock containingunsaturated hydrocarbons and the catalyst solution are thoroughlydehydrated. A controlled amount of tertiary butyl halide is added to thestream of fresh feed to be polymerized. The fresh feed and catalyststreams are separately chilled to the desired temperature and dischargedinto a vessel provided with a mixing means where the reactants are mixedas rapidly as possible and then allowed to remain in contact for apredetermined period of time. After the reaction has proceeded asufficient period of time to form the desired polymer, it is terminatedby suitable means, such as by adding to the reaction mixture a materialwhich destroys the activity of the catalyst, such as water or alcohol,and the polymer is then separated as the desired product.

It is to be emphasized that the activating effect of tertiary butylchloride or tertiary butyl bromide is obtained only when the compound isadded to the olefin feed and is not obtained when it is added to thecatalyst solution.

The operation described above is generally applicable to thepolymerization of low boiling tertiary base olefins, alone or inadmixture with low boiling conjugated diolefins in the presence of aFriedel-Crafts type catalyst to form polymeric hydrocarbons in range oflubricating oils and of viscous rubbery polymers. The reaction iscarried out at a temperature in the range of about -220 F. to about 200F., the particular temperature chosen within this range depending uponthe molecular weight of the polymer it is desired to form. In general,the lower the temperature employed within the aforementioned range, thehigher the average molecular weight of the polymer will be. For example,when it is desired to produce polymers in the molecular weight range oflubricating oils, reaction temperatures in the range of about -50 F. toabout 175 F. are preferably employed, the viscosity and the molecularweight of the product usually being lower with higher reactiontemperatures. Thus, at temperatures of around 175 F. polymers in the lowviscosity, relatively low boiling distillate range are obtained while attemperatures in the neighborhood of F., relatively high boiling viscouslubricating oils may be obtained. When it is desired to react lowboiling tertiary olefins, preferably in admixture with low boilingconjugated olefins, to form polymers which are rubber-like materials orvulcanizable gums at ordinary temperatures, lower reaction temperaturesare necessary, preferably in the range of about -50 F. and about 220 F.

Preferably the polymerization reaction is carried out within the rangeof about 100 F. to 1"I5 F. when it is desired to form vulcanizable gums.

Pressure has little, if any, influence on the course of the reaction;consequently, the reaction may normally be conducted at atmosphericpresthe molecular weight 4 sure when temperatures below the boilingpoints of the reactants are maintained. The reactants and the solventfor the catalyst should, however, be maintained in liquid phase duringthe reaction. The reaction is therefore conducted under suflicientpressure to maintain the reactants and the solvent in liquid phase. Theparticular pressure required will, of course, depend in each instanceupon the vapor pressure of the reactant mixture.

While the process of the present invention has been fully describedhereinbefore, this process is further illustrated by reference to anoperation wherein high molecular weight rubber-like polymers are formed.In such a process a mixture of a tertiary base olefin and a conjugateddiolefin may be employed and a catalyst may suitably be prepared byagitating dehydrated methyl chloride with substantially anhydrouspowdered aluminum chloride at a temperature of about 20 F. to give asolution of a concentration of about .1 to .5 gram of aluminum chlorideper cubic centimeters. The aforementioned feed mixture, comprising atertiary base olefin, such as isobutylene, having admixed therein from 2to 20 weight per cent based on the tertiary olefin of a conjugateddiolefln, such as butadiene or isoprene, may be dehydrated by passing itover a bed of calcium chloride or other suitable dehydrating agent. Thehydrocarbon feed stock may be dissolved in an alkyl halide, such asmethyl chloride, if desired, and the solution then chilled to about -40F. and passed into a vessel. The solution of aluminum chloride in methylchloride is chilled to a temperature slightly above the freezing pointof methyl chloride, say F., and the catalyst sprayed into the vesselthrough a nozzle while the diolefin-mono-olefin mixture in the vessel isbeing violently agitated. From 10 to 20 volume per cent of catalystsolution may be employed which may be added over a period ranging fromabout ten seconds to ten minutes. After the reactants have been incontact the desired interval of time, the reaction may be terminated bythe addition to the vessel of a large excess of water or alcohol. Thepolymer is then recovered and carefully washed to remove the catalystafter which the polymer may be dried and compounded as is desired. Inthe quenching step, the catalyst is intentionally destroyed in order toprevent further action beyond the desired polymerization. This quenchingstep can be effected by any hydrolyzing agent such as alcohol or water,but it is preferred to use hot water.

Although the foregoing describes a batch polymerization process, it isunderstood that the process may be made to operate on a continuous basisby constantly adding fresh feed and catalyst to the agitated reactionmixture and constantly removing the product as a slurry along withunconverted feed and methyl chloride.

The invention will be further illustrated by the following examples inwhich isobutylene and isoprene diluted with methyl chloride werepolymerized in a batch reactor. The methyl chloride was purified bytreatment with phosphoric anhydride. A catalyst solution containingaluminum chloride in an amount of 0.070 gram of aluminum chloride per100 cc. of solution was employed. To a chilled reactor was introduced1000 parts of a precooled feed comprising isobutylene, isoprene andmethyl chloride. The feed contained 25% isobutylene and a small amountof isoprene, amounting to 2.5 weight per cent of the isobutylene. Thefeedstock was charged to a cold reactor which had been. dried, purgedand blanketed with nitrogen. A stirring mechanism was attached and. ameans was provided for injection of catalyst solution. The feed stockwas cooled to 145 ll. and injection of catalyst solution was startedand. maintained at a constant rate equivalent to 0.004 part of aluminumchloride per minute. After the desired amount of catalyst had beenadded, the reactant mass, which was in the form of a slurry, wasagitated for an additional two minutes and the reaction stopped byaddition of alcohol- The reacted material was then further quenched bythe addition of hot water. The rubbery material was kneaded in EXAMPLEII The general. procedural steps employed in this example were similarto those described for Example I with reference to feed preparation,cata: lyst injection and polymer recovery except that the injection ofcatalyst was not discontinued after 0.02 part of catalyst had beenadded. Instead, each run was made with a different amount of catalyst toobtain difierent polymer yields. The amount of tertiary butyl chloridein the reaction mixture was kept constant at 6 parts per million foreach of the several runs. The data obtained from these runs are recordedin the. following the presence of hot water until a. crumbly body table:

' 7 Table II Catalyst A1013 1 Tertiar But I Efliciency, Lbs. i g ff g fCatalyst ili g Chlorid Add d of Polymer per IP g Added, R ta 6 to Feed,Parts Lb. of Catalyst 11 a S Parts $M? Per Million 1, 940 25. 0 e4 o.033 0. 005 e 2. 260 41. 4 10s 0. 047 0. 005 0 2,800 54.0 140 0.050 0.003c 2, 300 4 61.7 158 o. 067 0. 005 e 2, 350 70. 0 181 0. 077 0. 005 6 wasformed. The crumbs of polymer w EXAMPLEJIH strained and squeezed toremove as much entrained water as possible until the water content wasin the range of 10%. The weight of the polymer was recorded andcorrected for the amount of water remaining in the polymer mass. Fromthe data obtained on the weight of polymer pro- The several runs ofExample III were conducted in the same manner as those .of Example IIexcept that no tertiary butyl chloride was included in the reactionmixture. The data obtained from these runs are recorded in the followingtable:

duced, the catalyst efficiency and the conversion of olefin to polymerwere calculated.

EXAMPLE I Runs in accordance with the foregoing procedure were conductedwithout addition of tertiary butyl chloride and with addition oftertiary butyl chloride to the olefin feed in amounts varying from 16 to120 parts per million of reaction every respect were made using a twominute contact time between the catalyst and olefin. The data obtainedfrom these runs are recorded in the following table:

It will be noted from the foregoing data in Table I that the catalystefliciency and the amount of polymer produced is greatly increased atconversions below 20% by the addition of tertiary butyl chloride to thefeed. It is obvious from these data that the optimum promotionalconcentration of tertiary butyl chloride in the feed is 60 to '70 partsper million, as the catalyst efficiency was a maximum at thisconcentration. It is of great significance that very smallconcentrations (16 parts per million) of the activator have almost asmuch influence in initiating the reaction as the larger quantities. Inthis connection attention is directed to the column of Table I showingthe quantity of catalyst required to initiate the polymerizationreaction. It will be seen that in the run in which no tertiary butylTable I Catalyst Catalyst A1013 Tertiary Butyl Efficiency Lbs. 931333;gfi ggg Catalyst g l fgg Chloride Added of Polymer per Parts Added,Reaction to Feed, Parts Lb. of Catalyst Parts Parts per Million 0. 8 20. O2 0. 017 None 1, 900 14. 8 38 0. 02 0. 003 16 2, 250 1 7. 6 45 0. 02 0. 003 40* 2, 400 18.7 48 (l. 02 0.003 64 2, 100 16. 4 42 0. 02 0. 00380 2, 150 lb. 8 43 0. 02 0.003

7 chloride was added to the feed, the polymerization reaction wasinitiated only after 0.017 part of catalyst had been added. The lowcatalyst efficiency, conversion, and polymer yield reflect the lowactivity of the catalyst. During the remaining runs in which tertiarybutyl chloride was added to the feed the polymerization reaction startedalmost immediately upon the injection of catalyst solution into thereaction mixture as indicated by the very small quantities (0.003 partor less) of catalyst required to initiate the reaction.

By comparing the data of Example II and III, it will be seen that atconversions in excess of 25% the catalyst efficiency and the polymeryield is not appreciably affected by the employment of tertiary butylchloride as an activator in the reation mixture. On the other hand, thepowerful promotional efiect of the activator is observed by comparisonof the columns showing the grams of catalyst required to initiate thereaction in Example II in which 6 parts per million of tertiary butylchloride was added to the feed, and Example III in which no tertiarybutyl chloride was used. In the case Where 6 parts per million oftertiary butyl chloride was used as an activator, the polymerizationreaction was initiated after only 0.0030.005 part of aluminum chloridecatalyst had been added to the reaction mixture. In the case where noactivator was employed, the quan-' tity of catalyst required to initiatethe reaction was 0.017 part in all runs.

It should be emphasized that although the polymerization reaction iscaused to begin at much lower catalyst concentrations when employingtertiary butyl chloride as an activator than when this compound is notpresent, the yield of polymer and the catalyst efficiency areessentially the same at conversions above 25% irrespective of whetherthe activator is added or is left out of the reaction mixture. It is ofgreat significance, however, that at conversions below 25%, especiallywithin the range of 15 to 25 not only is the reaction initiated at lowercatalyst concentrations but also the yield of polymer and the catalystefiiciency is greatly increased by the presence or tertiary butylchloride in the reaction mixture.

The present invention has been described with reference to theproduction of elastomers by the low temperature polymerization of adiolefin and a tertiary olefin. It is to be understood that theactivating effects of tertiary butyl halide are not restricted to theproduction of elastomers but may also be realized in the polymerizationreaction wherein low molecular weight tertiary base olefins, alone or inadmixture with low molecular weight conjugated diolefins, are reacted toproduce lubricants and other desirable hydrocarbon products. In the caseWhere such unsaturated hydrocarbons are polymerized to yield lubricatingoils, a temperature in the range of 50 to 200 F. may be found desirable.

The nature and objects of the present invention having been fullydescribed and illustrated, what is claimed as new and useful and isdesired to be secured by Letters Patent is:

1. A process for polymerizing unsaturated hydrocarbons which includesthe steps of forming a substantially anhydrous feed stock at atemperature in the range of 220 F. and F. comprising a tertiary olefinhaving at least 4 and not more than '7 carbon atoms per molecule, analkyl halide and a material selected from the group consisting oftertiary butyl chloride and tertiary butyl bromide, the said materialbeing pres- 8 out in the feed stock in an amount in the range of 6 toparts per million parts of hydrocarbon in the feed stock, admixing saidfeed stock with a substantially anhydrous solution of a Friedel- Craftscatalyst chilled to substantially the same temperature as the feed stockto form a reaction mixture including a polymer, terminating the reactionand recovering said polymer.

2. A process for polymerizing unsaturated hydrocarbons which includesthe steps of forming a dehydrated feed stock at a temperature in therange of -220 F. and 0 F. comprising a tertiary olefin having at least 4and not more than 7 carbon atoms per molecule, a conjugated diolefinhaving at least 4 and not more than 7 carbon atoms per molecule, analkyl halide and a material selected from the group consisting oftertiary butyl chloride and tertiary butyl bromide, the said materialbeing present in the feed stock in an amount in the range of 6-100 partsper million parts of hydrocarbon in the feed stock, admixing said feedstock with a dehydrated solution of a Friedel-Crafts catalyst chilled tosubstantially the same temperature as the feed stock to form a reactionmixture including a polymer, terminating the reaction by adding to thereactants an agent for destroying the activity of the Friedel-Craitscatalyst and recovering said polymer.

3. A process for polymerizing unsaturated hydrocarbons which includesthe steps of forming a dehydrated feed stock at a temperature in therange of -220 F. and 0 F. comprising a tertiary olefin having at least 4and not more than '7 carbon atoms per molecule, a conjugated diolefmhaving at least 4 and not more than '7 carbon atoms per molecule, analkyl halide and a ma terial selected from the group consisting oftertiary butyl chloride and tertiary butyl bromide, the said diolefinbeing present in the feed stock in an amount in the range of 2 to 20% byweight based on the tertiary olefin in the feed stock and the saidmaterial being present in the feed stock in an amount in the range of 6to 100 parts per 5 million parts of hydrocarbon in the feed stock,

admixing said feed stock with a dehydrated solution of a Friedel-Craftscatalyst chilled to substantially the same temperature as the feed stockto form a reaction mixture including a polymer, terminating the reactionby adding an agent for destroying the activity of the Friedel-Craftscatalyst and recovering said polymer.

4. A process in accordance with claim 3 in which the tertiary olefin isisobutylene.

5. A process in accordance with claim 3 in which the diolefin isisoprene.

6. A process in accordance with claim 3 in which the Friedel-Craftscatalyst is aluminum chloride.

7. A process in accordance with claim 3 in which the agent fordestroying the activity of the catalyst is water.

8. A process for producing a polymer from unsaturated hydrocarbons whichincludes the steps of forming a dehydrated feed stock comprisingisobutylene, a conjugated diolefin having at least 4 and not more than 7carbon atoms per molecule, methyl chloride and a material selected fromthe group consisting of tertiary butyl chloride and tertiary butylbromide, the said diolefin being present in the feed stock in an amountin the range of 2 to 20% by weight based on the isobutylene in the feedstock and the said material being present in the feed stock in an amountin the range of 6 to 100 parts per million 9 parts of hydrocarbon in thefeed stock, chilling the feed stock to a polymerization temperature inthe range of 50 F. and 220 F., forming a dehydrated solution comprisingaluminum chloride and a solvent which does not react with the aluminumchloride, chilling said dehydrated solution to substantially the sametemperature as the feed stock, admixing said chilled dehydrated solutionwith the chilled feed stock to form a reaction mixture including apolymer, terminating the reaction by adding water to the reactionmixture and recovering said polymer.

9. A process in accordance with claim 8 in which the conjugated diolefinis isoprene.

DAVID C. WALSH, JR. HENRY G. SCHUTZE.

REFERENCES CITED The following references are of record in the file ofthis patent:

OTHER REFERENCES Getman and Daniels: Outlines of Theoretical Chemistry,6th ed., pp. 332, 333, Wiley (1937).

1. A PROCESS FOR POLYMERIZING UNSATURATED HYDROCARBONS WHICH INCLUDESTHE STEPS OF FORMING A SUBSTANTIALLY ANHYDROUS FEED STOCK AT ATEMPERATURE IN THE RANGE OF -220* F. AND 0* F. COMPRISING A TERTIARYOLEFIN HAVING AT LEAST 4 AND NOT MORE THAN 7 CARBON ATOMS PER MOLECULE,AN ALKYL HALIDE AND A MATERIAL SELECTED FROM THE GROUP CONSISTING OFTERTIARY BUTYL CHLORIDE AND TERTIARY BUTYL BROMIDE, THE SAID MATERIALBEING PRESENT IN THE FEED STOCK IN AN AMOUNT IN THE RANGE OF 6 TO 100PARTS PER MILLION PARTS OF HYDROCARBON IN THE FEED STOCK, ADMIXING SAIDFEED STOCK WITH A SUBSTANTIALLY ANHYDROUS SOLUTION OF A FREIDELCRAFTSCATALYST CHILLED TO SUBSTANTIALLY THE SAME TEMPERATURE AS THE FEED STOCKTO FORM A REACTION MIXTURE INCLUDING A POLYMER, TERMINATING THE REACTIONAND RECOVERING SAID POLYMER.